Struct NullifierTree 

pub struct NullifierTree { /* private fields */ }

The sparse merkle tree of all nullifiers in the blockchain.

A nullifier can only ever be spent once and its value in the tree is the block number at which it was spent.

The tree guarantees that once a nullifier has been inserted into the tree, its block number does not change. Note that inserting the nullifier multiple times with the same block number is valid.

Implementations

impl NullifierTree

pub const DEPTH: u8 = 64u8

The depth of the nullifier tree.

pub const UNSPENT_NULLIFIER: Word = EMPTY_WORD

The value of an unspent nullifier in the tree.

pub fn new() -> Self

Creates a new, empty nullifier tree.

pub fn with_entries( entries: impl IntoIterator<Item = (Nullifier, BlockNumber)>, ) -> Result<Self, NullifierTreeError>

Construct a new nullifier tree from the provided entries.

Errors

Returns an error if:

• the provided entries contain multiple block numbers for the same nullifier.

pub fn root(&self) -> Word

Returns the root of the nullifier SMT.

pub fn num_nullifiers(&self) -> usize

Returns the number of spent nullifiers in this tree.

pub fn entries(&self) -> impl Iterator<Item = (Nullifier, BlockNumber)>

Returns an iterator over the nullifiers and their block numbers in the tree.

pub fn open(&self, nullifier: &Nullifier) -> NullifierWitness

Returns a NullifierWitness of the leaf associated with the nullifier.

Conceptually, such a witness is a Merkle path to the leaf, as well as the leaf itself.

This witness is a proof of the current block number of the given nullifier. If that block number is zero, it proves that the nullifier is unspent.

pub fn get_block_num(&self, nullifier: &Nullifier) -> Option<BlockNumber>

Returns the block number for the given nullifier or None if the nullifier wasn’t spent yet.

pub fn compute_mutations<I>( &self, nullifiers: impl IntoIterator<Item = (Nullifier, BlockNumber), IntoIter = I>, ) -> Result<NullifierMutationSet, NullifierTreeError>

where I: Iterator<Item = (Nullifier, BlockNumber)> + Clone,

Computes a mutation set resulting from inserting the provided nullifiers into this nullifier tree.

Errors

Returns an error if:

• a nullifier in the provided iterator was already spent.

pub fn mark_spent( &mut self, nullifier: Nullifier, block_num: BlockNumber, ) -> Result<(), NullifierTreeError>

Marks the given nullifier as spent at the given block number.

Errors

Returns an error if:

• the nullifier was already spent.

pub fn apply_mutations( &mut self, mutations: NullifierMutationSet, ) -> Result<(), NullifierTreeError>

Applies mutations to the nullifier tree.

Errors

Returns an error if:

• mutations was computed on a tree with a different root than this one.

Trait Implementations

impl Clone for NullifierTree

fn clone(&self) -> NullifierTree

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for NullifierTree

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for NullifierTree

fn default() -> Self

Returns the “default value” for a type.

impl Deserializable for NullifierTree

fn read_from<R: ByteReader>( source: &mut R, ) -> Result<Self, DeserializationError>

Reads a sequence of bytes from the provided source, attempts to deserialize these bytes into Self, and returns the result.

fn read_from_bytes(bytes: &[u8]) -> Result<Self, DeserializationError>

Attempts to deserialize the provided bytes into Self and returns the result.

impl PartialEq for NullifierTree

fn eq(&self, other: &NullifierTree) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serializable for NullifierTree

fn write_into<W: ByteWriter>(&self, target: &mut W)

Serializes self into bytes and writes these bytes into the target.

fn to_bytes(&self) -> Vec<u8>

Serializes self into a vector of bytes.

fn get_size_hint(&self) -> usize

Returns an estimate of how many bytes are needed to represent self.

impl Eq for NullifierTree

impl StructuralPartialEq for NullifierTree